1. Field of the Invention
The present invention relates to transmission of image data between two image processing devices over a bi-directional communication interface, such as a local area network. More specifically, the invention involves negotiation between two devices such as an image output device and an image input device, so as to transfer image data between the devices, and so as to negotiate whether exportable image processing functionality on one device should be exported to the other device so as to increase overall image transfer efficiency.
2. Description of the Related Art
In local area networks and other environments providing bi-directional communication between connected devices, it is becoming increasingly common for such devices to communicate directly with each other so as to intelligently negotiate information exchange ordinarily without the need of a separate computer providing oversight. Once such negotiation protocol is JetSend™, which is a device-to-device communications protocol for local and wide area networks that allows network devices to intelligently negotiate information exchange. The JetSend™ protocol allows the two devices to connect over a network, to negotiate a common data type for the information exchange, to provide device status, and to exchange the needed information, all without intervention from a user or from a third device such as a computer which provides oversight over the communication between the two devices. JetSend™ protocol is described at length in “HP JetSend Communications Technology, Section I: Architectural Overview; Section II: Protocol References; and Section III: E-Material Specification”, Version 1.0, Hewlett Packard Co., 1997. These documents are incorporated by reference as if set forth in full herein.
One common example of information exchange is the exchange of image data between an image input device (such as a scanner or digital camera) and an image output device (such as a printer or facsimile or optical projector). According to currently-accepted information exchange negotiations, such as the JetSend™ negotiation, the image input device and the image output device jointly negotiate for a common data type for the image data, based on the image processing capabilities of the input and output devices, and thereafter exchange the image data in accordance with the negotiated data type. For example, in the case of an image data exchange between a color scanner and a monochrome printer, the scanner might include image processing capabilities so as to provide image data according to data formats that include full color image data and grayscale image data. The printer, on the other hand, might include image processing capabilities that allow it to accept full color image data, grayscale image data, and black-and-white image data, and thereafter to process such data so as to printout a monochrome image. For this contemplated information exchange, therefore, the most efficient data type for transfer of image data is grayscale image data, since it is commonly exportable and receivable by both the scanner and the printer, and since it results in the transmission of the least amount of data (and consequently the least amount of transmission time). Accordingly, for this information exchange, the scanner would scan in an image, convert the image into grayscale data, and transmit the grayscale data over the bi-directional communication interface to the printer; whereupon the printer would receive the grayscale image data from the bi-directional communication interface, convert the grayscale image data to monochrome image data, and print out the monochrome image data.
While such negotiations are advantageous in that they allow devices to negotiate a commonly-acceptable format for data transfer, improvements in efficiency are still needed. Specifically, because such negotiations fail to consider the relative processing power between the two devices, such negotiations often lead to a data transfer that is inefficient and time consuming.